Question about card randomness

[RainDog]

I recall reading at a few poker sites that the formula for generating random cards is seeded by user initiated events such as mouse clicks.

I've always been curious as to whether the formulas that sites use generate the cards all at once or one at a time (Is the river card determined at the same time the hole cards are?). Theoretically if the information preceeds the cards, than there is always the possibility that someone could find a way to access that information.

But the real reason I'm interested in this topic is because that age old "woulda coulda hit my flush, trips, straight, whatever" statement would be null and void because the very fact that you did fold the hand and the timing of your folding and mouse clicking changed the cards to come. So you can never REALLY know if you would have hit that flush right? Because even though I realize that the cards that come don't change the fact that a decision was right or wrong, I still always have a tiny little turn in my stomach when I fold a hand that would have won a big pot. However, if my folding changed the very outcome of the cards, then I can just be content to never know.